Want to know why NBC is giving up on five hours a week of prime-time programming and replacing it with Jay Leno? Take a look at this chart, pulled out of parent company GE’s investor presentation Tuesday.

To spell it out: Profits at NBC’s broadcast business–the NBC network along with revenue from local stations the network owns, and revenue from other stations that carry its programming–shrank from $1.4 billion in 2005 to $400 million this year.

That’s a billion dollars of profit that disappeared in three years (or a compound annual growth rate of negative 33 percent, if you like your stats served that way).

Bear in mind that GE (GE) is actually boasting here: It’s using the chart to pat itself on the back for making itself less dependent on broadcast advertising and revenue. Still, it’s always disconcerting to see a billion dollars disappear from the books, no matter how big and how well-positioned you are.

You can blame some of that loss on the fact that NBC has tumbled in the ratings and has never replaced the hits it had in the days of “Seinfeld,” and later, “Friends.”

But hits are cyclical: Wait around long enough, and you end up airing something that works. If NBC thought that hits would be enough to claw back some of that billion, CEO Jeff Zucker wouldn’t be conceding five valuable hours to Jay Leno, who costs less to air than the shows he’s replacing, but has less upside potential.

Instead, Zucker seems to be saying that broadcast TV is a big but shrinking business, and that he’s not going to fight that trend. Hard to argue with the numbers.

AllThingsD by Writer

AllThingsD.com is a Web site devoted to news, analysis and opinion on technology, the Internet and media. But it is different from other sites in this space. It is a fusion of different media styles, different topics, different formats and different sources. Read more »